//
// Created by 21577 on 2025/3/4.
//
#include<stdio.h>
int main(){
    int score;
    scanf("%d",&score);
    switch(score/10){
        case 10:
            printf("A");
            break;
        case 9:
            printf("A");
            break;
        case 8:
            printf("B");
            break;
        case 7:
            printf("C");
            break;
        case 6:
            printf("D");
            break;
        default:
            printf("E");
    }
    return 0;
}